how to acidify soil organically iron chloro sis

How to Acidify Soil Organically?

Plants grow amazingly well in the soil with low pH due to the enriched nutrients absorbed in the soil. With too high pH, plant health and optimal growth are affected to a considerable extent. In This post we will go into dept. on how to acidify soil organically.

Generally, it is harder for plants to absorb the nutrients from the soil with high alkalinity.

Maintaining the acidic soil pH is difficult as due to the presence of limestone in the soil, the alkalinity increases continuously. You can use some organic ways to lower the soil pH in gardens. Some of them are discussed in this article.

how to acidify soil organically iron chloro sis

Iron Chlorosis a condition that develops when the soil has inadequate acidity
Photo credit  Frank Vincentz

When Should I Acidify the Soil?

Now that you know a little bit of the soil pH, you must be wondering when might be the best time to acidify your soil.

First of all, the materials that acidify the soil can always be applied during any season of the year.

All in all, most of the products that may contain sulfur may take longer to leach into the soil during the cold season.

For that reason, the sulfur-based products are best applied during autumn.

Also, before anything else, it’s essential you know the current pH level of your soil. That’s one we recommend. Check for pricing on amazon.

This helps you to determine how much acid content you will need to add to the soil.

This can always be measured using a soil pH test that determines the alkalinity or acidity of the soil.

When the ph level is 7, the soil is considered to have a neutral pH while anything above 7 is considered alkaline.

On the other hand, any soil pH level below 7 is considered to have an acidic pH.

It pays to check the pH level of a garden before planting any ericaceous plants.

The pH testing of the soil can also be done any time of the year.

But if it’s done within three months after you add lime or any other organic matter to the soil the test may be somehow misleading.

Testing the Soil pH
The soil chemistry is a diverse and complex science.Therefore, if you want to be a successful gardener, let the pH testing of the soil be the first step before starting off farming in any new garden.

The pH testing for the soil can always be done in two very diverse ways which include;

⦁ One, you can use a soil test kit. The soil test kit is available at precisely any garden center or store.

⦁ The other method is by sending a sample of the soil from your garden to your local extension centers or laboratories for
Analysis and sampling.

How to Acidify Soil Organically? 1

An Example of Soil PH Testing kit
Photo Credit Lynn Betts

That being said, in case you opt for the home soil pH testing using the soil test kit, it is best if you use soil that has been scooped from a depth of about 4 inches deep.

All you need to do is take a spoonful of the soil sample then mix it with a reagent in a testing tube.

Afterward, you are required to wait until you observe the color change in the test tube.

You should use the results to compare the pH chart in order to determine the pH of the soil in your garden.

Easy Steps On How To Acidify Soil Organically

They always say, feed the soil and the soil will generously feed your plants.

Well, that’s entirely true. The soil you grow your plants in can either facilitate or hinder the growth of your plants.

This is because it’s like the foundation on which the entire garden grows.

The components of the soil always determine its quality and how well the plants will thrive.
For that reason, there is always the need to heed the specific needs of the plants by taking care of the soil accordingly.

And in organic gardening especially, building the soil is one of the major key factors to successful gardening. Therefore, below is a step by step guide on how to acidify soil organically.

Identifying the Type of Soil
Before you jump into the process of how to acidify soil organically, first you need to know the type of soil you got in your garden.

This a very crucial move but a lot more different from determining the soil ph. Soil type identification helps you to know which method is suitable for soil acidifying.

In that loosely attached and well-drained soil makes the acidification process a lot easier.

In that case, this category of soil is likely to realize the full benefits of the organic compounds added to the soil for acidification purposes.

The clumped clay soil, on the other hand, makes the acidification process a real hassle.

The fact that it is too compacted, the addition of organic materials will only make it more alkaline than acidic as expected.

Therefore, the best soil type to acidify is the loosely attached and well-drained soil.

Addition of the Organic Materials to the Ideal Soil Type
Organic matter is the best addition to this type of soil.

This is because the organic matter always acidifies the soil in bits as they break down.

All in all, the organic matter is required in quite large amounts for them to bring the ph down to the target level.

That being said, there are a number of nice materials that are organic you may consider. These include;
Manure and compost
⦁ Organic acidic mulches. This includes the pine needles
⦁ Composted oak leaves
⦁ Peat moss among others

how to acidify soil organically peat moss

Peat Moss 

Photo Credit Ragesoss

Peat moss lowers the soil pH gradually which is too easy to use for acid-loving plants. You just need to add two to three inches of peat moss to your garden soil and into the layers of topsoil underneath.

Addition of Elemental Sulphur

There is always the loose, well-drained soil but again there is the compacted clay soil.

In case yours falls under the compacted clay, sulfur might be the solution you’ve been searching for.

As discussed in the previous points, when you add organic matter to already dense soil could only make matters worse.

The soil is likely to retain the moisture’s hence making it twice as alkaline.

In that case, the most sure-fire way to acidify highly dense soil is by adding iron sulfate or sulfur to the soil.

That is because; elemental sulfur acidifies the soil since the bacteria present turns it to sulfuric acid.

In our case, it would take you about 2 pounds of the elemental sulfur content per every 100 square feet to lower a ph level of 7 all the way down to 4.5.

However, it’s important to know that elemental sulfur could take quite some time to react with the soil.

For that reason, it’s best if you add it to the soil precisely a year before you begin gardening.

This guarantees your ultimate results. Most importantly, ensure you work in the elemental sulfur up to 6 inches deep into the soil.

Addition of Iron Sulphate

In case you are wondering how iron sulfate has made it to this list; this is a compound that relies so much on chemical reactions in order to create the desired level of acidity.

In that case, unlike other compounds, iron sulfate is less dependent on some conditions such as temperature when compared to the elemental sulfur.

Elemental sulfur, unlike iron sulfate, depends on bacteria in order to produce the anticipated biological reaction. This makes it an ideal addition to the heavily compacted soil like clay.

In that case, it could take at least 10 pounds of the iron sulfate compound for a garden space of 100 square feet. This would reduce the ph level of the soil by at least one unit.

How to Acidify Soil Organically? 2

pH Scale

This means that, if you are planning on adding more than 10 pounds of the iron sulfate to the soil, you may have to split that into two different applications.

In that, the application could be spread out up to a period of two months.

This gives the soil enough space to absorb the iron sulfate applied.

Also, unlike the elemental sulfur, iron sulfate may take a shorter time to be absorbed n to the soil.

In that, it can successfully act on the target soil in a matter of four weeks.

This is a shorter period when compared to the months you have to wait for the elemental sulfur to act on the soil.

This means that iron sulfate could be used in the same month you are planning to plant.

All in all, you need to be careful with the application of the iron sulfate. This is because; it has been reported to cause rust stains on the patios, clothes, and sidewalks.

This means that you need to separate any clothes or equipment with iron sulfate from the rest.

This helps to avoid cases of cross-contamination.

Application of Vinegar

In case you are looking for a natural way on how to acidify soil organically , vinegar makes an ideal choice.

Vinegar works pretty well in fulfilling the task but this is only a short-term fix.

The vinegar will be absorbed into the soil then depleted all over again just when you are beginning to see some improvements in your plants.

Ensure that you water the plants with the mixture of vinegar and water for weeks until you realize some results.

Afterward, this process can be repeated after a few months.

Wood Ashes
Another organic method that you can use to raise the pH level of the soil in your garden is the addition of ash.

Wood ash contains calcium, potassium, and phosphate in considerable amounts, therefore, can do a great job on this.

However, wood ash is not as effective as lime but with constant use, it can help to improve the pH value of the soil significantly.

This applies mostly to the soil that is in a sandy nature.

All in all, you need to be careful when applying wood ash to the soil.

This is because it should not be let to come in to close contact with seedlings or roots. Reason being it could cause damage.

Wood ash should be spread in the garden lightly during winter then later blended in well during spring.

You need to keep track of yearly pH of your soil when using the wood ashes.

All in all, you need to be careful since too much of the wood ash could lead to nutritional deficiencies in the plants.

Final Verdict
There is a wide variety of organic substances that can be used to acidify the soil.

Most of the common ones include; manure, peat moss, and compost.

More specifically; the Canadian sphagnum peat moss has a pH between 3 and 4.5.

This means that peat moss is the ideal addition to the top soil that goes up to 8-12 inches deep in to the ground.

All in all, this option can be pretty expensive especially for the large areas.

For that reason, most of the gardener’s tend to avoid peat moss because of the sustainability issues.

Most of the professional gardeners recommend the use of pine needles, composted leaves and vegetables refuse.

This is because they are known to increase acidity in soil significantly too.

In that case, when it comes to how to acidify soil organically acidifiers, you should be in for some trial and error experiments before getting the ideal one for your garden.


  1. How do i organically neutralise acid sulfate soil?.

    • Hi Ivan! This is a topic for a future post. I looked around on the net and downloaded this pdf. I hope it helps..

  2. Juliann Negrete

    I can’t complete my order in your store!
    Why don’t you setup more stable processing like or charges 3%, just 0.1% and setup is free.

  3. Helpful information! Thanks Herminio….I’m a beginning gardener and just bought a moisture sensor/ph sensor. Well, I’ve overwatered all my gro bags and vegetable beds! Plus, the Ph of all the soils reads at about 8. Some leaves are turning yellow, and perhaps some fungi growth too, ugh! And I lost all my wooly thyme ground cover, new plants. Whew! I feel like a kindergartner with so much to learn…Thanks for your posts..

  4. I have clay soils so I really appreciated your suggestion of iron sulfate. I’ve added compost and the soil just got heavier. At least I’ve been mixing in perlite…

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